1. Field of the Invention
This invention relates to improvements in reciprocating piston engines. In particular, it relates to improvements in that portion of a reciprocating piston engine wherein power is delivered by the piston, or pistons, to the main drive shaft. The invention also relates to an improved metering device for the introduction of air, or a mixture of fuel and air into the engine.
2. Background and Prior Art
Reciprocating piston engines have been known for many years. In internal combustion engines, a type of reciprocating piston engine which has become widely available for both stationary and automotive uses, at least one and almost invariably a plurality of pistons are individually, reciprocably mounted within cylinders. A piston is constituted of a piston head, the crown or closed side of which faces the combustion chamber, or portion of a cylinder to which a charge of a combustible mixture, or fuel, can be admitted via a fuel injector or a carburator fed intake valve. The volume of the cylinder is varied by movement of the piston, the volume of the cylinder above the crown head of the piston expanding during the intake stroke, or piston outstroke, and decreasing during a piston exhaust stroke. The opposite side of a piston head is pivotally attached to an end of a piston shaft while the opposite end of a piston shaft is in turn operatively engaged to a crankshaft, A combustible mixture of fuel and air are fed into the closed end of a cylinder via a fuel intake valve, ignited, and burned such that the burning, expanding gases exert force against the crown side of a piston head in a power stroke, or piston outstroke to push, and move a piston within a cylinder, applying a torque to the crankshaft to perform useful work. Certain operating fundamentals are common to all internal combustion engines of the reciprocating piston type.
In the operation of an internal combustion engine an operating cycle or series of events are carried out in succession, over and over again, to make the engine run, or perform. Two-stroke and four-stroke engines are well known, the four-stroke engine being the most common. Considering, e.g., a single cycle of operation, with respect to a given cylinder of a operation of a four-stroke engine, there is included: (1) a fuel intake stroke produced by suction of fuel through an open intake valve into a closed cylinder during an outstroke of a piston, (2) a compression stroke produced by compression of the fuel attained by the instroke of a piston, (3) a power stroke attained by spark or self-ignition of the fuel charge sucked or injected into a cylinder, expansion of the burning gas pressing against the crown side of a piston head, and (4) an exhaust stroke attained by exhaust of the gases from the closed cylinder during the next instroke of a piston. These cycles are repeated ad infinitum, each cycle (i.e., intake, compression, power and exhaust stroke) producing two revolutions of the crankshaft.
The compression and power strokes are the basic and necessary strokes of the cycle of operation cf any reciprocating piston internal combustion engine. The fuel intake and exhaust strokes are eliminated in the two-stroke cycle engine by compressing the fresh fuel charge slightly outside the cylinders so that the fuel charge will flow into the cylinders through ports which are uncovered as the piston approaches the end of the power stroke. Exhaust gases are pushed out through a second set of ports in the cylinder in a scavenging step by the incoming fuel charge. It would be expected that the two-stroke cycle would provide twice as much power from an engine of given size at a given operating speed. Not so, however: the two-stroke cycle is less efficient than the four-stroke cycle becuase the four-stroke cycle provides more positive scavenging and charging of the cylinders with less loss of fuel charge to the exhaust. The two-stroke cycle, however, is somewhat more efficient in a self-ignition engine than in a spark-ignition engine because air alone is used in a self-ignition engine in scavenging the cylinders with no loss of fuel in the process.
Despite the wide availability and use of the internal combustion engine, in any event, such engines are notoriously fuel inefficient. The gasoline engine attains an efficiency of about fifteen to twenty-two percent, based on the theoretical useful energy available in a given weight, or volume of fuel. The diesel engine, one of the world's most efficient power sources, converts more of the energy contained in a given quantity of fuel into useful energy than any other power-developing engine. The future of the diesel engine thus appears assured because of its higher efficiency over an entire range of speed and load. Yet, the diesel engine is generally no more than about twenty-five to twenty-seven percent more efficient than a gasoline engine.
There presently exists a profound need for more fuel efficient reciprocating piston engines, especially internal combustion engines of the reciprocating piston type.